Comfort In Cabin Research Articles

Noise annoyance fuzzy index in passenger car cabin

Vehicle acoustical comfort and vibration in passenger car cabin are the factors which attract buyers to a vehicle, in order to have a comfortable driving environment. The comfort of the driving will affect the driver by influencing their driving performance. Vehicle acoustical comfort index (VACI) has been introduced to represent the level of annoyance in passenger car cabin. This index has been used in the computation related to the acoustics aspect in the car cabin. Noise annoyance is categorised into five states: most annoying, medium annoying, marginal, medium pleasant and most pleasant. In order to improve the VACI index, this study carries out an approach to classify and categorise the aforementioned five states using the fuzzy set theory approach. At the end of several studies, the noise annoyance fuzzy index (NAFI) has been introduced. By using NAFI, automotive researchers will be able to classify and make judgement about the state of annoyance from the exposed noise in the car cabin numerically, where the use of this index is regarded to be more precise and has practically been used in engineering fields especially where the fuzzy logic system is concerned.

Effects of aircraft cabin noise on passenger comfort

The effects of cabin noise on subjective comfort assessments were systematically investigated in order to reveal optimisation potentials for an improved passenger noise acceptance. Two aircraft simulation studies were conducted. An acoustic laboratory test facility provided with loudspeaker systems for realistic sound presentations and an aircraft cabin simulator (Dornier Do 728) with a high degree of ecological validity were used. Subjects were exposed to nine different noise patterns (three noise levels ranging from 66 to 78 dB(A) combined with three different frequency spectra). Regression analysis demonstrated a significant increase of passengers' acceptance with lower noise levels and significant effects of different frequency spectra determined by seat position in the aircraft cabin (front, middle, rear). Acoustic cabin design should therefore consider measures beyond noise level reduction altering noise characteristics to improve passengers' comfort and well-being in the aircraft cabin. Practitioner Summary: To improve passenger comfort in the aircraft with respect to cabin noise, passengers' reactions to specific noise conditions were systematically investigated. Two laboratory studies showed significant dose-response relationships between sound pressure level and subjective comfort ratings which differed due to the noise at specific seat positions in the aircraft.

Interaction between vehicle exterior design and perceived loudness of vehicle acceleration sound

To increase cabin comfort, not only decreasing sound pressure level but also improving the sound quality is essential. In addition, when the sound quality of the vehicle matches with the exterior design, the sound is considered to be perceived more attractive. In this study, to investigate the relationship between the perceptions of the sound and the exterior design, the loudness of acceleration sounds were evaluated with vehicle exterior images. In the loudness evaluation test, 10 acceleration sounds and 10 exterior images were prepared and half of the images were luxury vehicle images and the others were sporty vehicle images. The experimental subject evaluated the loudness of presented sound with the luxury or sporty vehicle exterior image. Twenty one male subjects participated in the test. Eleven of them drove vehicles frequently and the others were infrequently. As a result, frequently driving subjects felt the acceleration sound louder by having luxury vehicle impression. In contrast, infrequently driving subjects felt the sound softer by having the same vehicle impression. Consequently, it was clarified that perceived loudness was influenced by vehicle exterior design, and the tendency was changed depending on the driving frequency.

Experimental investigation of thermal comfort and air quality in an automobile cabin during the cooling period

The air quality and thermal comfort strongly influenced by the heat and mass transfer take place together in an automobile cabin. In this study, it is aimed to investigate and assess the effects of air intake settings (recirculation and fresh air) on the thermal comfort, air quality satisfaction and energy usage during the cooling period of an automobile cabin. For this purpose, measurements (temperature, air velocity, CO2) were performed at various locations inside the cabin. Furthermore, whole body and local responses of the human subjects were noted while skin temperatures were measured. A mathematical model was arranged in order to estimate CO2 concentration and energy usage inside the vehicle cabin and verified with experimental data. It is shown that CO2 level inside of the cabin can be greater than the threshold value recommended for the driving safety if two and more occupants exist in the car. It is also shown that an advanced climate control system may satisfy the requirements for the air quality and thermal comfort as well as to reduce the energy usage for the cooling of a vehicle cabin.

Effect of Solar Radiation on Thermal Comfort in an Automobile Cabin

The aim of this study is to evaluate effect of solar radiation on thermal comfort in an automobile during cooling period with experiments. High cabin interior temperature, especially in summer months, causes discomfort for driver and the passengers. In the study, ambient temperature, relative humidity, mean radiant temperature and mean skin temperature of the driver inside the automobile cabin during cooling period for same ventair velocities with different solar radiation values were measured in a parked car. Subjective survey was performed during the experiments to the driver. Experiments were held under real conditions and the results were compared with answers taken from the subject and discussed. Adequate thermal comfort conditions were not obtained for high solar radiation values but it was found that thermal comfort conditions inside the cabin were quite acceptable for low solar radiation values.

Fuzzy-based Temperature and Humidity Control for HV AC of Electric Vehicle

Vehicles are the people's main means of transportation and thermal comfort in the vehicle cabin plays an important role. The heating, ventilating, and air-conditioning (HVAC) operation system in the vehicle cabin decides the degree of comfort, traffic safety as well as health of the occupants. The challenge of designing the HVAC control is to automatically achieve the thermal comfort, regardless of time varying weather conditions. Since most HVAC systems are complex with nonlinearity, distributed parameters, and multivariable therefore many classical controls do not necessarily yield a satisfactory control performance. This paper presents the development of temperature and humidity control strategy for HVAC based on Fuzzy Logic Control (FLC). The goal of the FLC-based temperature control is to satisfy the convergence and equilibrium property. The simulation test results have been shown a satisfactory to control the temperature and humidity.

Sound Transmission Loss Prediction of the Composite Fuselage with Different Methods

Increase of sound transmission loss(TL) of the fuselage is vital to build a comfortable cabin environment. In this paper, to find a convenient and accurate means for predicting the fuselage TL, the fuselage is modeled as a composite cylinder, and its TL is predicted with the analytical, the statistic energy analysis (SEA) and the hybrid FE&SEA method. The TL results predicted by the three methods are compared to each other and they show good agreement, but in terms of model building the SEA method is the most convenient one. Therefore, the parameters including the layup, the materials, the geometry, and the structure type are studied with the SEA method. It is observed that asymmetric laminates provide better sound insulation in general. It is further found that glass fiber laminates result in the best sound insulation as compared with graphite and aramid fiber laminates. In addition, the cylinder length has little influence on the sound insulation, while an increase of the radius considerably reduces the TL at low frequencies. Finally, by a comparison among an unstiffened laminate, a sandwich panel and a stiffened panel, the sandwich panel presents the largest TL at high frequencies and the stiffened panel demonstrates the poorest sound insulation at all frequencies.

크루즈선 객실의 공조 쾌적성 평가에 관한 연구

The present work focuses on the evaluation of thermal comfort in passenger cabin of a cruise ship. A computational fluid dynamics (CFD(Airpak)) is used to calculate air velocity and temperature distribution in the passenger cabin as well as PMV and PPD. The CFD is used to simulate two different cases, room unit system and wardrobe duct system. Both of cases are simulated in summer environment condition. The room unit system and wardrobe duct system are compared and evaluated by ISO 7730 thermal comfort categories. The performance of room unit system is shown to be more effective for this typical case of passenger cabin.

Local and overall thermal comfort in an aircraft cabin and their interrelations

In this study the interrelation between local and overall thermal comfort of passengers in aircraft cabins was investigated by thirteen simulated flights. For each of the tests forty test persons filled out questionnaires concerning their perceived overall and local thermal comfort at temperatures of 20 °C–25 °C, which were measured at every second seat. With these physical and subjective data PMV (Predicted Mean Vote) and TSMV (Thermal Sensation Mean Vote) of test persons as well as PPD (Predicted Percentage of Dissatisfied) and PD (Percentage of Dissatisfied) were compared. The PMV was consistently similar to the TSMV, while the thermal dissatisfaction in tests was always higher than PPD. The hypothesis at the beginning of this study was that the high ratio of thermal dissatisfaction in the aircraft cabin reported in literature might be caused by local discomfort. Therefore statistical analyses about the interrelations between local and overall thermal comfort were performed and models indicating such interrelations were developed. Some local perceptions are significantly different from overall thermal perception and these body segments alter in dependence of the overall thermal environment. Also body segments rated similarly were detected and these segments were pooled to distinct body regions using principal component analysis. Under the same overall thermal sensation the local thermal perception on a certain body region predominantly influenced the overall thermal comfort. Therefore weighting factors of local body regions on the overall thermal comfort were determined in dependence of the overall thermal sensation by means of multiple linear regression models.

Study on the Thermal Accumulation and Distribution Inside a Parked Car Cabin

Problem statement: When a vehicle is parked under the direct sun, the accumulated heat is affecting many interiors inside the vehicle cabin, such as the vinyl materials of the dashboard, the leather covers and the electronic components. Also, it represents an uncomfortable operating period fo r the passengers. The studies under this topic are en titled by the vehicle manufacturers as Vehicle Cabin Comfort. Approach: In the present study, experimental and numerical a nalyses were conducted. The experimental results were obtained f rom measurements on a salon car parked in un- shaded area. Six different cases had been investiga ted consisting of full windows closing case, four different windows opening settings and sun shade us age case. The temperature at 12 different locations inside the car had been recorded for many days and the mean values are used as initial and boundary conditions to run the 3-D computational simulation. The CFD simulation was carried out by FLUENT software. Results: Both experimental and CFD simulation results revealed that the most hot air was accumulated in the top part of the cabin and natura l circulation take place with large scale cavity du e to natural heat transfer from the dashboard and the re ar windshield. The drop down of the front side windows by 20 mm caused reduction in the front air gap by 20%. The sunshade on the front had considerably reduced the heat accumulation inside t he cabin, where the dashboard surface temperature dropped by 26% and the maximum air temperature was found to be 27% lower. Conclusion: The use of the sunshade and/or dropdown windows on both sides reduced the heat accumulation due to fresh air exchange with the exterior environment.

Acoustical aspects of travel comfort in the aircraft cabin

In several European projects tests were conducted during real flights and in aircraft simulators in order to identify important parameters of travel comfort. Physical environmental, physiological and questionnaire data were measured and investigated with respect to human perception. Besides numerous intrinsic quantities affecting health, well-being and awareness of ambience defined measurable environmental parameters influence flight and cabin crews' as well as passengers' perception, psychology and physiology. Sound and vibration are relevant environmental parameters with impact on passenger and crew. Other important influence is caused by e.g. air quality, pressure, local climate. Statistical analysis of the collected data reveals significant correlations between environment and human response for selected groups of test persons. A specific acoustic comfort is not well defined but part of common well-being and comfort. The demand for a general human response model is discussed, which relates ambience and perception.

Active noise control in light jet aircraft

Active systems for noise reduction are especially of interest when considering applications in which low-frequency noise is a main source of disturbance and only limited amounts of installation space and payload are available. This makes the adaptation and implementation of such systems plausible in vehicles such as automobiles and aircraft where passive reduction methods are restricted. In order to achieve effective active control in these environments, aspects such as the control method and actuator- and sensor-type as well as positioning must be considered. The noise characteristics are often known beforehand or are easily accessible by measurement. Using this data, an upper bound for possible noise reduction may be determined, e.g., by means of linear prediction methods. A current research project is aimed at developing an audiosystem for the cabin area of a light jet aircraft which, at the same time, should also function as an effective noise reduction system in order to enhance the cabin comfort as well as the audio quality. Using data from a measurement flight in a typical light jet aircraft, limitations of active control are determined. Furthermore, the testbed, an acoustic mockup, is presented, currently beholding a multichannel ANC- Audio system for tonal and broadband noise.

Assessment of thermal comfort in a car cabin with sky-roof

The need to address the problem of thermal comfort inside a car cabin is becoming more significant for the automobile industry especially as recent developments in vehicle styling entail an increase in the glazed surfaces of the car, in particular for sky-roof models. The extended glazed surfaces produce an increase in radiative thermal loads on the area involved and so greater attention is being given to the enhancement and upgrading of the heating, ventilation, and air-conditioning system capacity, and efforts are being made to find solutions to the problem of thermal comfort inside the cabin. This paper is a first experimental study which focuses on assessing the performance of four different types of special laminated sky-roof (with a low-emissivity internal surface). A performance comparison between special and traditional sky-roofs has been carried out in a field test (on the road) in summer conditions. The main results show that the special sky-roofs allow the temperature inside the car cabin to be reduced.

Storage air conditioning: For hybrid vehicles with automatic start-stop function

Irrespective of their degree of hybridization, hybrid vehicles are all fitted with a start-stop function that shuts off the engine when the vehicle is idling in order to reduce fuel consumption and emissions. The fuel saving results from the engine stopping, and, to a small degree, from the fact that the A/C compressor cuts off at the same time. When the compressor is switched off in summer, the cabin temperature climbs rapidly, and climate comfort is lost. With the help of the storage evaporator, a new development from Behr, the climate comfort in the passenger cabin can be maintained in 95% of all idle stop phases in city/environs traffic.

Local evaluation of thermal comfort

Increasing demand for a comfortable cabin environment makes it necessary, as early as the construction phase, to estimate what effect different factors will have on the driver and passenger. Full-scale measurements and numerical simulations have been carried out in order to investigate how well computational fluid dynamics (CFD) and thermal manikins are able to predict the perceived thermal climate. The heat loss from real or virtual manikins interacts with the environment around the body, as well as thermal interaction with windows; ventilation and seat are influencing the manikins. When manikin heat loss is linked to human thermal sensations in new comfort zone diagrams, the local as well as total thermal situation can be clearly presented. Simulations of this type will enable engineers to make better decisions and early predictions in the design and construction process, improving the thermal comfort in the vehicle environment.

Comfortable vehicle air conditioning

A comfortable cabin climate is an important aspect of vehicle design. In turn, this puts ever-increasing demands on the climate control system, making it necessary to install complex sensor systems capable of registering control variables and disturbance variables. A crucial factor in this context is the sun’s thermal effect on the inside temperature of the vehicle. Accordingly vehicles with automatic air conditioning systems have been equipped with a solar sensor that registers the intensity of the sun’s rays. Sensors have developed from simple mono-sensors to bus sensors with integrated controllers. With the recently developed ISoS (Intelligent Solar Sensor), Behr-Hella Thermocontrol has come up with a new kind of sensor based on a revolutionary concept.

Aircraft sound quality for passenger comfort and enhanced product image

Passenger cabin noise requirements for commercial airplanes are being expanded beyond the traditional focus on noise annoyance and speech intelligibility. There is increasing recognition that the passenger response to the cabin soundscape is much more complex; affecting perceptions of product quality, and impacting fatigue and comfort. Tailoring the soundscape for a preferred cabin environment requires the development of metrics that capture a range of passenger responses. In a preliminary exploration of potential metrics, a series of experiments were undertaken to investigate passenger preference for several classes of stationary and transient sounds within the passenger cabin. The design, implementation, and data analysis for these experiments is discussed, along with the application of results to enhance cabin comfort and to convey product quality. Key findings confirm what has been found in sound quality studies in other industries: sound level alone does not fully account for passenger preference.

1425 トラクタキャビン内部空間の音響解析に基づくANCの2次音源配置(GS-10 制御手法,研究発表講演)

Agricultural tractors are operated at high engine revolutions. Then, the operator hears annoying engine noises. The aim of this study is to improve cabin comfort by ANC system. In this paper, we examine ANC system arrangement based on an acoustical analysis inside the tractor cabin. By arranging secondary sources, increase of the controlled effect and Expansion of the controlled range is expected. We arrange secondary sources in an effective place based on acoustical analysis inside the agricultural tractor cabin. For the acoustical analysis, the finite element model of inside the agricultural tractor cabin and acoustic analysis software SYSNOISE was used. The control loudspeaker and error microphones are to be outside of the sound pressure nodal area at target frequencies. We decide the arrangement of secondary sources by sensitivity analysis. The arrangement determined in analysis was the most effective and the control range was the widest.

1210 FASTECH360S(新幹線高速試験電車)における快適性向上の取組み(OS5 交通・物流システムのサービス・快適性の向上,一般講演)

1210 FASTECH360S(新幹線高速試験電車)における快適性向上の取組み(OS5 交通・物流システムのサービス・快適性の向上,一般講演)

Evaluation of thermal comfort in a vehicle cabin

The objective of the work presented in this article was to study the airflow in a vehicle cabin with the typical dimensions and geometry of a multi-purpose vehicle (MPV) with a view to evaluating the thermal comfort through the equivalent temperature index. Tests were carried out on a life-size laboratory model of a car cabin, constructed with a simplified geometry, for different conditions: with and without the presence of a thermal mannequin, with different values of air velocity and temperature and with different regulation of the air inlets. The values of equivalent temperature were determined for each one of the various parts of the body, by two distinct forms: from the measurements performed by the thermal mannequin and from the physical parameters of the airflow, i.e. air velocity and temperature. The mapping of these flow parameters inside the cabin was done through a scanning process carried out with a traversing mechanism with eight low-velocity thermal anemometer probes, controlled from the exterior of the car cabin. Thus, using the values measured in plans in the neighbourhood of the different parts of the thermal mannequin, the equivalent temperature profiles were computed during tests carried out without the presence of the thermal mannequin.